diff --git a/changelog.d/5293.bugfix b/changelog.d/5293.bugfix
new file mode 100644
index 000000000..aa519a843
--- /dev/null
+++ b/changelog.d/5293.bugfix
@@ -0,0 +1 @@
+Fix a bug where it is not possible to get events in the federation format with the request `GET /_matrix/client/r0/rooms/{roomId}/messages`.
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index 255a85c58..b92c6a9a9 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -475,6 +475,8 @@ class RoomMessageListRestServlet(ClientV1RestServlet):
         if filter_bytes:
             filter_json = urlparse.unquote(filter_bytes.decode("UTF-8"))
             event_filter = Filter(json.loads(filter_json))
+            if event_filter.filter_json.get("event_format", "client") == "federation":
+                as_client_event = False
         else:
             event_filter = None
         msgs = yield self.pagination_handler.get_messages(